libgo/go/net/fd_poll_runtime.go

   1 // Copyright 2013 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // +build darwin dragonfly freebsd linux netbsd openbsd windows solaris
   6
   7 package net
   8
   9 import (
  10         "runtime"
  11         "sync"
  12         "syscall"
  13         "time"
  14 )
  15
  16 // runtimeNano returns the current value of the runtime clock in nanoseconds.
  17 func runtimeNano() int64
  18
  19 func runtime_pollServerInit()
  20 func runtime_pollOpen(fd uintptr) (uintptr, int)
  21 func runtime_pollClose(ctx uintptr)
  22 func runtime_pollWait(ctx uintptr, mode int) int
  23 func runtime_pollWaitCanceled(ctx uintptr, mode int) int
  24 func runtime_pollReset(ctx uintptr, mode int) int
  25 func runtime_pollSetDeadline(ctx uintptr, d int64, mode int)
  26 func runtime_pollUnblock(ctx uintptr)
  27
  28 type pollDesc struct {
  29         runtimeCtx uintptr
  30 }
  31
  32 var serverInit sync.Once
  33
  34 func (pd *pollDesc) init(fd *netFD) error {
  35         serverInit.Do(runtime_pollServerInit)
  36         ctx, errno := runtime_pollOpen(uintptr(fd.sysfd))
  37         runtime.KeepAlive(fd)
  38         if errno != 0 {
  39                 return syscall.Errno(errno)
  40         }
  41         pd.runtimeCtx = ctx
  42         return nil
  43 }
  44
  45 func (pd *pollDesc) close() {
  46         if pd.runtimeCtx == 0 {
  47                 return
  48         }
  49         runtime_pollClose(pd.runtimeCtx)
  50         pd.runtimeCtx = 0
  51 }
  52
  53 // Evict evicts fd from the pending list, unblocking any I/O running on fd.
  54 func (pd *pollDesc) evict() {
  55         if pd.runtimeCtx == 0 {
  56                 return
  57         }
  58         runtime_pollUnblock(pd.runtimeCtx)
  59 }
  60
  61 func (pd *pollDesc) prepare(mode int) error {
  62         res := runtime_pollReset(pd.runtimeCtx, mode)
  63         return convertErr(res)
  64 }
  65
  66 func (pd *pollDesc) prepareRead() error {
  67         return pd.prepare('r')
  68 }
  69
  70 func (pd *pollDesc) prepareWrite() error {
  71         return pd.prepare('w')
  72 }
  73
  74 func (pd *pollDesc) wait(mode int) error {
  75         res := runtime_pollWait(pd.runtimeCtx, mode)
  76         return convertErr(res)
  77 }
  78
  79 func (pd *pollDesc) waitRead() error {
  80         return pd.wait('r')
  81 }
  82
  83 func (pd *pollDesc) waitWrite() error {
  84         return pd.wait('w')
  85 }
  86
  87 func (pd *pollDesc) waitCanceled(mode int) {
  88         runtime_pollWaitCanceled(pd.runtimeCtx, mode)
  89 }
  90
  91 func (pd *pollDesc) waitCanceledRead() {
  92         pd.waitCanceled('r')
  93 }
  94
  95 func (pd *pollDesc) waitCanceledWrite() {
  96         pd.waitCanceled('w')
  97 }
  98
  99 func convertErr(res int) error {
 100         switch res {
 101         case 0:
 102                 return nil
 103         case 1:
 104                 return errClosing
 105         case 2:
 106                 return errTimeout
 107         }
 108         println("unreachable: ", res)
 109         panic("unreachable")
 110 }
 111
 112 func (fd *netFD) setDeadline(t time.Time) error {
 113         return setDeadlineImpl(fd, t, 'r'+'w')
 114 }
 115
 116 func (fd *netFD) setReadDeadline(t time.Time) error {
 117         return setDeadlineImpl(fd, t, 'r')
 118 }
 119
 120 func (fd *netFD) setWriteDeadline(t time.Time) error {
 121         return setDeadlineImpl(fd, t, 'w')
 122 }
 123
 124 func setDeadlineImpl(fd *netFD, t time.Time, mode int) error {
 125         diff := int64(time.Until(t))
 126         d := runtimeNano() + diff
 127         if d <= 0 && diff > 0 {
 128                 // If the user has a deadline in the future, but the delay calculation
 129                 // overflows, then set the deadline to the maximum possible value.
 130                 d = 1<<63 - 1
 131         }
 132         if t.IsZero() {
 133                 d = 0
 134         }
 135         if err := fd.incref(); err != nil {
 136                 return err
 137         }
 138         runtime_pollSetDeadline(fd.pd.runtimeCtx, d, mode)
 139         fd.decref()
 140         return nil
 141 }